JP2011016670A - Method for synthesizing vanadate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new method for synthesizing vanadate which has high mass-productivity.SOLUTION: RbCOpowder is only brought into contact with VOpowder at room temperature in the air to subject RbCOand VOto a solid-phase reaction and obtain crystalline RbVO. CsCOpowder is only brought into contact with VOpowder at room temperature in the air to subject CsCOand VOto the solid-phase reaction and obtain crystalline CsVO.

Description

  The present invention relates to a method for synthesizing vanadate.

CsVO ₃ and RbVO ₃ that are vanadates are known to be highly efficient phosphor materials that exhibit host emission (Non-Patent Document 1). And recently, this phosphor material exhibits unusually high fluorescence quantum efficiency (CsVO ₃ : 87%, RbVO ₃ : 79%) as a fluorescent material that does not contain a rare earth, and performs continuous vacuum ultraviolet irradiation. It became clear that this material can be formed into a film at room temperature on an organic substrate (nonpatent literature 2).

Zeitscrift fuer Physik, 147, 350-360 (1957) Direct Fabrication of Metavanadate Phosphor Films on Organic Substrates for White Light Emitting Devices, T. Nakajima, M. Isobe, T. Tsuchiya, Y. Ueda and T. Kumagai; Nature Materials 7 (2008) 735

  However, the vacuum ultraviolet irradiation device is a special and expensive device and has no mass productivity.

  In view of the above problems, an object of the present invention is to provide a novel method for synthesizing a vanadate having high mass productivity.

As a result of various investigations to achieve the above-mentioned problems, a solid-state reaction proceeds by simply bringing Rb ₂ CO ₃ powder and V ₂ O ₅ powder into contact at room temperature and in air, and crystalline vanadate can be obtained. The present invention was completed.

That is, in the method for synthesizing the vanadate of the present invention, a solid-phase reaction of Rb ₂ CO ₃ and V ₂ O ₅ is achieved only by bringing Rb ₂ CO ₃ powder and V ₂ O ₅ powder into contact at room temperature in the air. Thus, crystalline RbVO ₃ is obtained.

In addition, by bringing Cs ₂ CO ₃ and V ₂ O ₅ powder into contact with each other only at room temperature and in air, Cs ₂ CO ₃ and V ₂ O ₅ are allowed to undergo a solid phase reaction to obtain crystalline CsVO _3. Features.

  ADVANTAGE OF THE INVENTION According to this invention, the synthesis | combining method of the novel vanadate with high mass productivity is provided.

Is a photograph of contacting the rb ₂ CO ₃ powder and _V 2 _{O 5} powder. Photo taken by irradiating UV light with a wavelength of 365 nm after 5 minutes, 15 minutes, 45 minutes, 60 minutes, 6 hours have passed since the Rb ₂ CO ₃ powder and V ₂ O ₅ powder were contacted in air at room temperature It is. It is a photograph taken by irradiating ultraviolet rays with a wavelength of 365 nm when 5 minutes, 15 minutes, 45 minutes, and 60 minutes have passed since the Rb ₂ CO ₃ powder and the V ₂ O ₅ powder were brought into contact with each other at room temperature under an argon atmosphere. . Room temperature, an X-ray diffraction patterns after mixing the _Rb 2 CO ₃ powder and _V 2 _{O 5} powder in air. Room temperature, is a SEM image after mixing the _Rb 2 CO ₃ powder and _V 2 _{O 5} powder in air. Room temperature, the emission spectrum and the excitation spectrum of RbVO ₃ obtained by mixing _Rb 2 CO ₃ powder and _V 2 _{O 5} powder in air. It is a chromaticity diagram of fluorescence emission of RbVO ₃ obtained by mixing Rb ₂ CO ₃ powder and V ₂ O ₅ powder in air at room temperature. The rb ₂ CO ₃ powder and V ₂ O ₅ powder slurry prepared by mixing with water was applied to a plastic substrate, at room temperature, a thin film photograph of RbVO ₃ obtained by drying in air. Room temperature, an X-ray diffraction patterns after mixing the _Cs 2 CO ₃ powder and _V 2 _{O 5} powder in air. 6 is an excitation spectrum and emission spectrum of CsVO ₃ obtained by mixing Cs ₂ CO ₃ powder and V ₂ O ₅ powder in air at room temperature, and is shown superimposed on the excitation spectrum and emission spectrum of RbVO ₃ in FIG. It is a thing.

The method for synthesizing the vanadate according to the present invention comprises a solid phase reaction of Rb ₂ CO ₃ and V ₂ O ₅ only by bringing Rb ₂ CO ₃ powder and V ₂ O ₅ powder into contact at room temperature and in air. Crystalline RbVO ₃ is obtained.

In addition, Cs ₂ CO ₃ and V ₂ O ₅ powder are brought into contact with each other only in the air at room temperature in the air to obtain a crystalline CsVO ₃ by causing a solid phase reaction between Cs ₂ CO ₃ and V ₂ O _5. is there.

This solid-phase reaction starts and proceeds only by bringing Rb ₂ CO ₃ powder and V ₂ O ₅ powder or Cs ₂ CO ₃ powder and V ₂ O ₅ powder into contact at room temperature and in air. Do not need.

In addition, when bringing the Rb ₂ CO ₃ powder and the V ₂ O ₅ powder into contact with each other or when bringing the Cs ₂ CO ₃ powder and the V ₂ O ₅ powder into contact with each other, by adding a slight amount of water, The solid-phase reaction between Rb ₂ CO ₃ and V ₂ O ₅ or the solid-phase reaction between Cs ₂ CO ₃ and V ₂ O ₅ can be promoted.

  Thus, according to the present invention, unlike the conventional synthesis method, the vanadate can be easily synthesized without requiring firing. In addition to the phosphor material, the present invention is also expected to develop into other material fields such as a catalyst, a pigment, and an electrode material.

In addition, a slurry prepared by mixing Rb ₂ CO ₃ powder and V ₂ O ₅ powder, or Cs ₂ CO ₃ powder and V ₂ O ₅ powder with water is applied to a substrate and dried at room temperature, thereby producing crystals. A thin film of crystalline RbVO ₃ or crystalline CsVO ₃ can be obtained. That is, a phosphor material thin film can be obtained by an ordinary coating method without using a vacuum system such as a vacuum ultraviolet irradiation device. The thin film thus obtained is considered to be applicable to flexible lighting, wavelength conversion films for solar cells, and the like.

  In general, the synthesis of inorganic phosphors requires heat treatment as in the case of ordinary ceramic materials, and no examples have been known in which a crystalline phosphor material is crystallized without a special process at room temperature.

  Hereinafter, description will be made based on specific examples.

As shown in FIG. 1, the Rb ₂ CO ₃ powder and the V ₂ O ₅ powder were brought into contact with each other at room temperature in the air. When observed while irradiating ultraviolet rays having a wavelength of 365 nm, as shown in FIG. 2, fluorescence was observed from the contact interface between the Rb ₂ CO ₃ powder and the V ₂ O ₅ powder, and the Rb ₂ CO ₃ and V ₂ O ₅ It was confirmed that the solid phase reaction was progressing. When the Rb ₂ CO ₃ powder and the V ₂ O ₅ powder are brought into contact with each other in an argon atmosphere at room temperature, as shown in FIG. 3, the contact interface between the Rb ₂ CO ₃ powder and the V ₂ O ₅ powder is used. Fluorescence was not observed.

FIG. 4 shows an X-ray diffraction pattern after mixing Rb ₂ CO ₃ powder and V ₂ O ₅ powder at room temperature and in air. When compared with the simulated pattern, the respective peaks matched, and it was confirmed that crystalline RbVO ₃ was formed in a single phase.

FIG. 5 shows an SEM image after mixing the Rb ₂ CO ₃ powder and the V ₂ O ₅ powder in the air at room temperature. It was confirmed that fine particles having an average particle diameter of 1 μm or less were obtained.

FIG. 6 shows an excitation spectrum and an emission spectrum of RbVO ₃ obtained by mixing Rb ₂ CO ₃ powder and V ₂ O ₅ powder in air at room temperature. White light emission with a broad emission wavelength centered in the green region, which is excited by near ultraviolet rays and has high visibility.

FIG. 7 shows a chromaticity diagram of fluorescence emission of RbVO ₃ obtained by mixing Rb ₂ CO ₃ powder and V ₂ O ₅ powder in air at room temperature. Although it was slightly yellowish green, the value was shown in the white area.

A slurry prepared by mixing Rb ₂ CO ₃ powder and V ₂ O ₅ powder with water was applied to a plastic substrate and dried in air at room temperature.

A photograph of the resulting thin film of RbVO ₃ is shown in FIG. Even when the substrate was bent, the thin film did not peel off.

Cs ₂ CO ₃ powder and V ₂ O ₅ powder were brought into contact with each other in air at room temperature. Similar to Example 1, crystalline CsVO ₃ was obtained.

FIG. 9 shows an X-ray diffraction pattern after mixing Cs ₂ CO ₃ powder and V ₂ O ₅ powder in air at room temperature. Compared with the case of RbVO ₃ , the reaction was a little slower and a little of the raw material remained, so the peak of the raw material was also observed, but when compared with the simulated pattern, it was confirmed that crystalline CsVO ₃ was formed in the main phase It was done.

FIG. 10 shows the excitation spectrum and emission spectrum of CsVO ₃ obtained by mixing Cs ₂ CO ₃ powder and V ₂ O ₅ powder in air at room temperature. White light emission with a broad emission wavelength centered in the green region, which is excited by near ultraviolet rays and has high visibility.

Claims (2)

Rb ₂ CO ₃ and V ₂ O ₅ powder are contacted with each other at room temperature in the air to cause a solid phase reaction between Rb ₂ CO ₃ and V ₂ O ₅ to obtain crystalline RbVO ₃ Method of synthesizing vanadate. Room temperature, and characterized by obtaining a _Cs 2 CO ₃ powder and _V 2 _{O 5} powder _Cs 2 CO ₃ only by contacting a and _V 2 _{O 5} and the by solid-phase reaction crystalline CSVO ₃ in the air Method of synthesizing vanadate.